Railway signal



Nov. 27, 1934.

C. H. LARSON RAILWAY S I GNAL Filed Dec. 31, 1930 2 Sheets-Sheet 1 Jfivenwfi Q2234 arsn Nov. 27, 1934. c. H. LARSON 1,982,439

RAILWAY S IGNAL Filed Dec. 31, 1930 2 Sheets-Sheet 2 Patented Nov. 27, 1934 PATENT OFFICE UNITED STATES RAILWAY SIGNAL Carl H. Larson, Elkhart, Ind., assignor to The Adlake Company, a corporation of Illinois The invention relates to signal lamps for railways such as are used on semaphores, and has for its principal object to provide a signal having primary and auxiliary lamps, the latter being automatically put into service upon failure of the primary lamp; to provide circuits for the primary and auxiliary lamps which carry direct and alternating currents with equal efficacy, and which are adapted to maintain a constant voltage across the lamp filament in service whether primary or auxiliary, or whether the current is direct or alternating; and to mount the currentcontrolling and regulating devices on the lamp in such manner as to permit access to them without danger of disturbing the bulbs and the mechanism by which they are carried.

The invention is especially adapted to be used in railway signal circuits normally supplied with alternating current but provided with storage batteries arranged to be cut in upon breakdown of the generator or failure of the alternating .current supply for any reason. The voltage in these lines is often as low as 3 /2 and is rarely greater than 13%. In no case within my experience has more than 16 volts been used.

A desirable and practicable embodiment of the invention is shown and described inthe accompanying drawings, in which Fig. 1 is an elevation of the current-controlling and regulating devices, a detail of the lamp casing and of the housing for the regulating mechanism, the latter being shown in section;

Fig. 2 is a sectional detail on the line 2-2 of Fig. 1;

Fig. 3 is a view on the line 3- 3 of Fig. 1; Fig. 4 is a diagram of the lamp circuits; Fig. 5 is a front elevation of the lamp; and Fig. 6 is a sectional view thereof on the line 6-6 of Fig. 5.

The lamp casing is represented at 10, and is provided with a lens 12 and with suitable means, such as the bracket 11, by which it may be attached to a support. A hinged door 13, secured 5 by a clasp 14, aifords access to the interior of the casing. 7

Within the casing there is mounted a suitable standard 15, which carries the service and emergency bulbs 16, 19, the former being positioned at the focal point of a reflector 1'7, carried by a support 18. 7 The standards 15 and 18 are mounted upon a plate 20, pivotally attached to the bottom of the casing 10. Suitable wires within the casing provide local circuits for the two bulbs. A conduit 21, leading to the casing, incloses the conductors 22, 23, which supply current to the lamp.

As thus far described the lamp is without novelty.

The controlling and regulating devices for the local circuits are mounted on the outer face of a plate 24, of insulating material, which is suitably attached to the outer surface of a wall of the casing, covering an aperture 25 therein. This plate is provided with suitable binding posts for the main line conductors 22, 23, and for the local leads to the two bulbs.

In Fig. 4 the binding posts for the main conductors are indicated at 26, 27, and those for the local circuits at 28, 29. These posts project through the opening 25 into the lamp chamber.

The controlling and regulating devices comprise a relay 30 in the local circuit of the service bulb 16, and a reactance coil 31 in the local circuit of the bulb 19-, both of these coils being connected with the binding post 27. Anormally closed switch 32, 34', in the lead to the reactance coil is openable by the relay 30 when current is supplied to the lamp, and the local circuit of the bulb 16 is uninterrupted. Any interruption in this circuit, as by the failure of the bulb, automatically results in the closing of the circuit to the bulb l9.

The circuits of the controlling and regulating 7 devices (Figs. 1 and 3) comprise a line 33, leading from the post 27 through the coil of the relay 30 to the binding post 29, from which the local circuit to the service bulb leads. The line 33 is also electrically connected with a-stationary switch element 34, with which the movable member 32 of the switch cooperates. From the latter member the current is conveyed, when the switch is closed, through a line 35 to the impedance coil 31, and from the latter through a line 36 to the binding post 28, from which leads a line to the emergency bulb 19.

The switch element 32 is carried by one arm of an L-shaped armature 38 of the relay 30, this armature being pivotally supported by a bracket 39 preferably of brass, carried by the core 40 of .the relay. The member of the armature 38 which carries the switch element 32 being substantially horizontally disposed, drops by gravity when the relay is not energized and closes the switch.

When the service bulb is in use the core of the relay 30 attracts the armature 38, separating the switch elements 32, 34, and thus cutting out the emergency bulb.- Upon failure of the service bulb, as by the burning out of its filament, the switch is closed by gravity and current is 'supplied to the emergency bulb. The local circuits of bothbulbs are connected with the binding Post 26.

The small voltages at which the lamp is designed to operate make it important that the switch 32 be firmly closed to supply the auxiliary bulb with suflicient current, and this requires the relay structure to be made fairly rugged and heavy, as shown. With a relay of such proportions the unavoidable alternating current losses due to impedance are correspondingly high and are a very considerable fraction of the low voltages supplied to the lamp. The

current values and bulbs are of course so se-' lected that the main bulb will be operatively energized when alternating current travels through its local circuit. Inclusion of the reactance coil 31 in the auxiliary bulb circuit balances the two local circuits, whether alternating or direct current be used, so that either current may energize to full illumination the bulb in whichever local circuit happens to be closed.

The core of the relay 30 being U-shaped as shown in Fig. 1 forms with the armature 38 a substantially closed magnetic circuit which is equal in reactance to that of the coil 31. It will be understood that the resistance of the relay 30 and coil 31 are also equal so that the two have equal impedance to the flow of alternating or direct current. This makes it possible to use the two kinds of current interchangeably, it being necessary, of course, to employ an alternating current of slightly higher voltage if the absolute voltage across the filament is to be the same as when direct current is used. This is so because of the voltage drop due to self induction in an alternating current circuit. By mounting the controlling and regulating devices upon the exterior of the lamp casing, as upon the plate 24 attached thereto, the local circuits of the lamp are so short that their resistance is negligible, and furthermore, these devices are accessible without disturbing the signaling elements.

A housing 41 provided with a weatherproof seal incloses the controlling and regulating devices, and is detachably secured to the lamp casing.

Various changes in the details of construction may be made within the scope of the appended claims.

I claim as my invention- 1. A railway signal lamp comprising a service and an auxiliary incandescent bulb of similar electrical characteristics, line wires connected with the lamp, local circuits for the two bulbs, a normally closed cut-out switch in the circuit of the auxiliary bulb, a relay including a reactance coil in the circuit of the service bulb for opening the switch, and a reactance coil in the auxiliary bulb circuit the impedance of the two coils being substantially the same whereby the auxiliary bulb is automatically cut in by the failure of the service bulb and the current served to the lamp may be equalized whether the current employed be direct or alternating.

2. A railway signal lamp comprising a service and an auxiliary incandescent bulb of similar electrical characteristics, a main line circuit leading to the lamp, normally closed local circuits for the two bulbs, a cut-out switch in the circuit of the auxiliary bulb, a relay having the characteristics of a reactance coil in the circuit of the service bulb for open ng the switch, and a reactance coil in the circuit of the auxiliary bulb, the impedance of the two circuits being substantially the same, whereby the current impressed upon the circuits of the two bulbs may be equalized whether it be direct or alternating.

3. In a railway signal lamp having a service and an auxiliary bulb of similar electrical characteristics, a local circuit for each bulb, electromagnetic means in said service bulb circuit for opening the circuit of the auxiliary bulb, and a reactance coil in the auxilary bulb circuit of equal impedance with the electro-magnetic means whether the current be direct or alternating.

CARL H. LARSON. 

